I doubt most people trading after hours even listened to the conf call. For one thing PETM management is usually pretty conservative with their estimates. For 1st Q they are giving estimates of .92 - .97 with analyst estimates at .94. On the conf call when asked about the full year guidance all they said was that they are comfortable with that guidance and "we'll see what happens". Other than that everything on the call was pretty good. Gross margins are not falling. Super premium and premium foods are doing very good and now account for 75% of food sales. They will be opening up 45-50 net new stores PLUS 12 microstores (I think they are about 6-7k sq ft.). Microstores will have less SKU's but they will include services like pet grooming (and vet I think).
I originally bought PETM at the end of 2011. Since then I've occasionally sold a few shares close to 70 and bought shares back when they dipped. I picked up some shares @ 61.75 after hours. I think the story is still good.. Sounds like they are just sandbagging.